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Maternal microchimerism and protection against asthma

Published Online: February 25, 2013

Maternal asthma and a child’s sex are significant and reproducible risk factors for the development of asthma. Although the mechanisms for these effects are unknown, they likely involve non-classical genetic mechanisms. One possible explanation involves microchimerism (Mc), which refers to the presence of small numbers of non-self cells in an individual. The normal exchange of cells between mother and fetus during pregnancy is the most common source of Mc, and the presence of maternal cells in her offspring is referred to as maternal microchimerism (MMc).

In a study published in The Journal of Allergy and Clinical Immunology (JACI), Thompson et al hypothesized that some of the observed risks for asthma may be due to different rates of transmission or persistence of maternal cells to children of mothers with asthma compared to children of mothers without asthma, or to sons compared to daughters. They further theorized that rates of MMc differ between children with and without asthma. The researchers tested these hypotheses in 317 subjects from three independent cohorts. Using real-time quantitative PCR, MMc was detected in 20.5% of subjects. Significantly lower rates of asthma were observed among MMc positive subjects compared to MMc negative subjects (P=0.029). Neither maternal asthma nor sex of the child was a significant predictor of MMc.

The authors conclude that the transfer and persistence of maternal cells to her offspring during pregnancy may protect against the development of asthma, suggesting a previously unexplored mechanism influencing asthma risk. Future work may suggest a mechanism by which persistent maternal chimeric cells protect against childhood asthma, and may lead to novel therapeutic interventions.

The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.